Numerous bodies of water such as rivers, lakes, ponds, streams, brooks, drinking water supplies, irrigation systems, agricultural water systems, aquariums, fountains or ornamental water systems, fish ponds, swimming pools, shower rooms and industrial water systems, such as cooling towers and ponds, frequently have an excessive growth of algae and other microorganisms, which impart an unacceptable quality to the body of water. Moreover, some of the enumerated bodies of water develop excessive aquatic weed growth, which interferes with the flow of water and renders the body of water unsuitable for the intended use or diminishes the economic value of it. Weeds and algae in the recited bodies of water are controlled by various means, including chemical algaestats, algaecides, and herbicides.